These vessels are not produced in anything like the same numbers as the Federation Runabouts, even accounting for the smaller Romulan fleet. This has lead to some speculation that the vessels suffer from an undisclosed design fault, perhaps in the warp drive system. A more likely answer is that relatively high warp capability of this model makes it too expensive to be worth producing in very large quantities, and it is likely that the Romulans operate slower classes of shuttles - perhaps variants on this one - to make up the difference.